Retractable leashes for dogs and other animals are very well known. They typically feature a housing containing a spool rotatably mounted on the axle. A flexible cord has a first end having a clip, which may be attached to a collar on an animal. A second end of the cord passes through an opening in the housing and connects rigidly to the spool. A spring causes the spool to preferentially rotate in a first direction so as to wind the cord onto the spool. When the spool rotates in a second direction so as to unwind the cord, tension is placed on the spring. In the case of a leash, the housing is hand-held; in the case of an anchored tether, the housing may be mounted to a wall, a floor, or the ground.
Once the first end of the cord is connected to the animal's collar, the animal's distance from the spool determines the amount of tension on the spring. As the animal pulls away from the spool, he pulls on the cord, causing the spool to rotate in the second direction so as to pay out the cord. This applies tension to the spring. When the animal moves toward the spool, the tension on the spring is released, causing the spool to rotate in the first direction so as to wind the cord onto the spool.
The spring used in these retractable leashes is very light and substantially constant, so that the animal is able to move freely. No significant resistance is offered by the spring as the cord pays out. This is advantageous because, it would be tiring for both the animal and the owner to have to pull against the resistance exerted by a strong spring. What is less advantageous about this spring is that it is easy for the animal to run off, hitting the end of the cord with great force and potentially pulling the housing of a hand-held leash out of the owner's hand. Also, since most leashes are mounted to a collar around the animal's throat, when the animal reaches the end of the cord, the cord can potentially cause discomfort or possible injury to the animal by pulling the collar sharply against the animal's throat. Similarly, a large dog could potentially uproot a tether mounted in the ground.
Other desirable features possessed by most retractable animal tethers include a mechanism to lock the lead at a fixed length, allowing the owner to maintain tight control over the animal. Also, these retractable tethers include a brake that can be used to immediately stop an animal. This is important because, if the animal approaches another animal or a person in a threatening way, the owner must be able to immediately stop forward momentum of the animal.
It is also known to provide leashes having shock absorbers positioned on the cord, near the animal. As the animal reaches the end of the leash, this is intended to attenuate the force of the impact of the animal's collar, which is attached to the leash, against the animal's throat, resulting in reduced discomfort to the animal. However, these shock absorbers are bulky and add additional weight to the end of the leash connected to the animal's collar. Also, the shock absorbers of the prior art do not allow an owner to instantly stop forward movement of the animal, should it be necessary to do so. This is because the shock absorbers typically attenuate shock through the use of springs or similar structures at the pet's end of the leash, beyond the reach of the owner. These springs allow the cord to reversibly extend when the animal pulls on the leash.
It is an object of this invention to provide a retractable leash having a variable resistance.
It is a further object of the invention to provide a retractable leash having a reduced likelihood to cause discomfort or injury to an animal.
It is a third object of the invention to provide a retractable leash which provides both a pet and his owner with feedback, letting them know when the pet is approaching the end of the leash. This allows both to react.
It is a fourth object of the invention to provide a retractable pet leash which provides both a mechanism for providing increased resistance to forward momentum by a pet as it approaches the end of the leash, and a braking mechanism for halting forward momentum by the pet at any time.
It is a fifth object of the invention to provide a retractable pet which is more comfortable for the pet owner to use.